1. Field of the Invention
The present invention relates to a method of producing an organic transistor which enables a simultaneous production of plural organic transistors, and an organic transistor which can be produced by the above-mentioned method of producing an organic transistor.
2. Description of the Related Art
A semiconductor transistor typified by TFT shows the current trend towards spreading of its applications along with the development of display devices. Such a semiconductor transistor functions as a switching element when the electrodes are connected through a semiconductor material.
As the semiconductor material used for the semiconductor transistor, inorganic semiconductor materials such as silicon (Si), gallium arsenic (GaAs) and indium gallium arsenic (InGaAs) have been used. Semiconductor transistors using such an inorganic semiconductor material are also used for display TFT array substrates of liquid crystal display devices which have been widely spread in recent years.
On the other hand, organic semiconductor materials made of organic compounds are known as the semiconductor material. Organic semiconductor materials. have an advantage in that: they are allowed to be increased in area at a lower cost than those using the inorganic semiconductor materials, and they can be formed on a flexible plastic substrate and are also stable against mechanical impact. Therefore, active studies are being made as to technologies regarding the organic semiconductor materials, which is assumed to be applied for display devices such as flexible displays typified by electronic papers in the next generation.
When producing an organic semiconductor transistor using an organic semiconductor material like this, it is usually necessary to form the organic semiconductor layer in pattern form. The vacuum deposition method using a metal mask has been mainly used to form an organic semiconductor layer in pattern form so far (for example, Seungmoon Pyo et al, “Low-temperature processable inherently photosensitive polyimide as a gate insulator for organic thin-film transistors” Appl. Phys. Lett. 86,133508 (2005)). The vacuum deposition method is superior in that a layer made of an organic semiconductor material can be patterned into a desired pattern with high accuracy. However, the vacuum deposition method has a problem of being poor in its productivity because vacuum conditions need to be fulfilled, a large amount of organic semiconductor materials adhered to a mask are wasted, and the like, so that its process is complicated and costly.
Therefore, there has been no method provided to directly form an organic semiconductor layer in pattern form by a simple method.